The following relates generally to operating a memory array and more specifically to transition metal doped germanium (Ge)-antimony (Sb)-tellurium (Te) (GST) and related memory devices.
Memory devices are widely used to store information in various electronic devices such as computers, wireless communication devices, cameras, digital displays, and the like. Information is stored by programming different states of a memory device. For example, binary devices have two states, often denoted by a logic “1” or a logic “0.” In other systems, more than two states may be stored. To access the stored information, a component of the electronic device may read, or sense, the stored state in the memory device. To store information, a component of the electronic device may write, or program, the state in the memory device.
Various types of memory devices exist, including magnetic hard disks, random access memory (RAM), read only memory (ROM), dynamic RAM (DRAM), synchronous dynamic RAM (SDRAM), ferroelectric RAM (FeRAM), magnetic RAM (MRAM), resistive RAM (RRAM), flash memory, phase change memory (PCM), and others. Memory devices may be volatile or non-volatile. Non-volatile memory (e.g., FeRAM, PCM, RRAM) may maintain their stored logic state for extended periods of time even in the absence of an external power source. Volatile memory devices (e.g., DRAM) may lose their stored state over time unless they are periodically refreshed by an external power source.
Chalcogenide material compositions may be used in components of a phase change memory cell—e.g., in a selector device or memory element. These components may have a first threshold voltage at which they become conductive (current is allowed to flow through the composition) when in an amorphous state and a different threshold voltage when in a crystalline state, and the difference between the first threshold voltage and the second threshold voltage may be referred to as threshold voltage window. In some cases, a sensing window of a phase change memory cell depends on the threshold voltage window of a corresponding chalcogenide material—e.g., a sensing window may increase as the threshold voltage window of the chalcogenide material increases. However, memory components having larger threshold voltage windows may in some cases also have slower crystallization (or SET) speeds (the speed with which the composition transitions from an amorphous to a crystalline state), which may decrease the operational speed of a corresponding memory cell. Improved memory devices are desired.